Field of the Invention
The present disclosure relates to a power module in which a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is incorporated, and to a three-phase inverter system including this power module. The present disclosure further relates to a method of testing a power module.
Description of the Background Art
A power module in which a power MOSFET and a freewheeling diode connected in anti-parallel with the power MOSFET are incorporated has been brought into practical use. In such a power module, a Schottky barrier diode characterized by a high-speed switching operation and a low forward voltage drop is often used as the freewheeling diode (see for example WO2010/004802).
One of failure modes of the MOSFET (also referred to as MOS transistor) is degradation of a body diode resulting from energization thereof. This failure occurs when forward current is continuously applied to a PN junction diode like a body diode, due to growth of a stacking fault in an epitaxial layer caused by electron-hole pair binding energy. Particularly in the case where a wide-bandgap semiconductor such as SiC (silicon carbide) and GaN (gallium nitride) and the like is used as a semiconductor material, the stacking fault is likely to occur and therefore this failure mode is likely to present a problem.